1. Field of the Invention
This invention generally relates to ammunition and, more specifically, to munitions with an increased initial velocity projectiles.
2. Description of the Background Art
Ammunition cartridges have been in use for nearly as long as hand-held firearms, dating back to 1586. Cartridges are used with muzzle-loading military firearms as well as for sports shooting.
The history of bullets even predates the history of firearms, having been originally made out of stone or clay balls used as sling ammunition as weapons and for hunting. As firearms became more technologically advanced, from around 1500 to 1800, bullets changes very little. They remained simple round (spherical) lead balls called rounds differing only in their diameter.
The first pointed or “conical” bullets were designed for the British army in 1823, bullets have evolved since then and the modern bullet was developed in 1892 when the copper jacketed bullet, an elongated bullet with a lead core in a copper jacket, was-invented.
The surface of lead bullets fired at high velocity may melt due to hot gases behind and friction with the bore. Because copper has a higher melting point, and greater specific heat capacity and hardness, copper jacketed bullets allow greater muzzle velocities. The velocity of bullets increased with advances in aero-dynamics. These bullets traveled for greater distances more accurately and carried more energy with them.
Bullet design must address two primary problems. In the barrel they must first form a seal with the gun's bore. If a strong seal is not achieved, gas from the propellant charge leaks past the bullet thus reducing the efficiency and accuracy of the bullet. The bullet must also engage the barrel of the weapon without damaging or excessively fouling the gun's bore and without distorting the bullet which would also reduce accuracy. These interactions between the bullet and the bore are termed “internal ballistics”.
Bullets for older firearms were classically molded from pure lead. This worked well for low speed bullets fired at velocities of less than 1,475 (ft/s). For higher speed bullets fired in modern firearms a harder alloy of lead and tin works well. For even higher speed bullets jacketed coated lead bullets are used. The common element in all of these bullets is lead, which is widely used because it is very dense, thereby providing a high amount of mass and, thus, kinetic energy for a given volume.
At speeds of greater than 1000 ft/s, common in most handguns, lead is deposited in riffle bores at an ever increasing rate. A cup made of a harder metal, such as copper, placed at the base of the bullet and called a “gas check” is often used to decrease lead deposits by protecting the rear of the bullet against melting when fired at higher pressures but this, too, does not solve the problem at higher velocities.
Bullets intended for even higher-velocity applications generally have a lead core that is jacketed or plated with a thin layer of gilding metal, such as cupronickel, copper alloys or steel. The thin layer of harder metal protects the softer lead core when the bullet is passing through the barrel and during flight which allows delivery of the bullet intact to the target. The heavy lead core delivers its kinetic energy to the target. Full metal jacket bullets are completely encased in the harder metal jacket except for the base. Steel bullets are often plated with copper or other metals for corrosion resistance during long periods of storage. The invention can also increase the initial velocities in non-cartridge-based munitions such as in canons where amorphous metallic alloy can be used to reduce energy losses generated by the propellant by covering the wadding or even the outer surfaces of the projectile with amorphous metallic alloy to maximize energy transfer to projectiles.
U.S. Pat. Nos. 6,244,187; 8,291,828 and 8,434,410 disclose attempt to increase the velocities of bullets. These patents also present descriptions of prior art attempt at increasing velocities of bullets and are incorporated as if fully set forth herein. As extensively discussed in U.S. Pat. No. 6,244,187 bullet manufacturers have produced bullets within a relatively narrow range of velocities ranging from 2000 f/ps-2700 f/ps. This is done to balance the different parameters, including exit velocities, range, penetration, etc. There is still a need to make cartridges more efficient and increase bullet velocities by harnessing as much of the energy released by the propellant without sacrificing the other properties of the bullet.